Pulmonary function tests (PFTs) are performed at hospital-based pulmonary labs, outpatient pulmonology clinics, and independent diagnostic testing centers. Most people find a location through their primary care doctor, who writes the order and refers them to a nearby facility. If you already have a pulmonologist, their office likely has testing equipment on-site or a dedicated lab they work with.
Types of Facilities That Offer PFTs
The most common setting is a pulmonary function laboratory within a hospital system. Large academic medical centers, like UCSF Health, operate dedicated pulmonary function labs staffed by respiratory therapists who specialize in diagnostic testing. These labs typically offer the full range of tests: basic spirometry, lung volume measurements, diffusion capacity testing, and challenge tests for exercise-induced or medication-triggered airway narrowing.
Outside of hospitals, many private pulmonology practices and multispecialty clinics perform PFTs in-office. These are often more convenient for scheduling and parking, though they may not offer every specialized test. Independent diagnostic centers are another option, particularly in areas without a major hospital system nearby. Some primary care offices have basic spirometry equipment, but for a complete pulmonary function workup, you’ll typically be sent to a specialized lab.
To find a facility near you, start with your insurance company’s provider directory or call your primary care doctor’s office. They usually have a short list of labs they refer to regularly. You can also search your nearest hospital system’s website for “pulmonary function laboratory” to see what’s available.
Do You Need a Referral?
In almost all cases, yes. PFTs are ordered by a physician, not something you can walk in and request. Your primary care doctor or a specialist writes the order specifying which tests you need, then refers you to a testing facility. Some insurance plans require a formal referral before they’ll cover the test, so check with your plan ahead of time. When you go to your appointment, bring your photo ID, insurance card, and any referral or requisition forms.
The tests themselves are performed by pulmonary function technicians (respiratory therapists with specialized training in diagnostic testing), and the results are interpreted by a board-certified pulmonologist. Your referring doctor typically receives the results within about three business days.
Remotely Supervised Spirometry
If getting to a lab is difficult because of distance, mobility, or health concerns, remotely supervised spirometry is an emerging option worth asking about. In this setup, you’re trained on a portable spirometry device during a clinic visit, then perform follow-up tests at home while a technician watches and coaches you through a video call in real time.
A study comparing remotely supervised home spirometry to traditional lab-based testing found no significant difference in the quality of results. Accurate readings for key measurements were achieved 75-78% of the time at home versus 81-86% in the lab, a gap that was not statistically meaningful. This held true even for patients over 65. Researchers concluded that remotely supervised spirometry could actually be superior to basic spirometry done in a primary care office, since the technician providing real-time guidance is a specialist. This option isn’t widely available everywhere yet, but it’s worth asking your doctor about if travel to a lab is a barrier.
Consumer spirometers you can buy online are a different story. Without professional supervision, the accuracy drops considerably, and the results generally aren’t accepted for clinical diagnosis or monitoring.
How to Prepare for Your Test
Preparation matters because certain substances directly affect your airways and can skew results. The National Heart, Lung, and Blood Institute provides specific timelines for what to avoid before testing.
Do not smoke on the day of your test. If you’re having diffusion studies (which measure how well gases pass from your lungs into your blood), avoid both smoking and alcohol the entire day. For exercise-related testing, don’t smoke for at least 8 hours, skip caffeine for 12 hours, and avoid eating for 3 hours beforehand.
The bigger preparation issue is your medications. If your test includes a before-and-after comparison with a bronchodilator (an inhaler that opens your airways), you’ll need to stop using your current inhalers on a specific schedule:
- Short-acting rescue inhalers (like albuterol): stop 6 hours before
- Short-acting anticholinergic inhalers (like ipratropium): stop 12 hours before
- Long-acting inhalers (like salmeterol or formoterol): stop 24-36 hours before
- Ultra-long-acting inhalers (like tiotropium): stop 36-48 hours before
Your doctor’s office should give you specific instructions when you schedule the test. If they don’t, call and ask, because showing up unprepared can mean rescheduling.
What Happens During the Test
PFTs are noninvasive. You won’t need needles, sedation, or any recovery time. The core of most testing sessions involves breathing into a mouthpiece connected to a device that measures airflow and volume. A nose clip keeps air from escaping through your nostrils.
For spirometry, the most common component, you’ll take the deepest breath you can and then blow out as hard and fast as possible, sustaining the exhale until your lungs are completely empty. The technician will coach you through each attempt and will likely ask you to repeat it several times to get consistent readings. It’s more physically demanding than people expect. Blowing that hard for that long can make you lightheaded or tired, which is normal.
Lung volume testing may involve sitting inside a clear, phone-booth-sized chamber called a body plethysmograph. You breathe normally while the chamber measures pressure changes to calculate the total amount of air your lungs can hold. It looks intimidating but is painless.
Diffusion capacity testing requires you to breathe in a small amount of a harmless tracer gas, hold your breath for about 10 seconds, then exhale. The machine measures how much of that gas your lungs absorbed, which reveals how efficiently oxygen moves from your airways into your bloodstream.
If your doctor ordered a methacholine challenge test (used to diagnose asthma), you’ll inhale gradually increasing concentrations of a substance that narrows the airways, with spirometry repeated after each dose to see how your lungs respond. This test takes longer and is only done in facilities equipped to manage a strong airway reaction.
Choosing a Quality Lab
Unlike radiology departments or blood labs, pulmonary function laboratories in the United States don’t currently have a mandatory accreditation program. Countries like Canada, Australia, and New Zealand have formal accreditation systems, and the American Thoracic Society has been developing a U.S. program modeled after those international standards. Labs that participate would be accredited for five-year periods with a renewal process.
Until formal accreditation becomes widespread, look for labs that follow American Thoracic Society and European Respiratory Society (ATS/ERS) testing standards. Hospital-based labs at academic medical centers are generally a safe bet, since they’re staffed by specialized technicians and overseen by board-certified pulmonologists. If you have a choice between facilities, ask whether the lab follows ATS/ERS guidelines and whether a pulmonologist reviews all results. Those two factors are the closest proxies for quality you can evaluate on your own.